Is there an app/website where users can contribute exercises and tests plus solutions (like a wiki)?

I'm talking about exercises based on facts, sciences, math etc. Wikiversity as an example offers that, but it is more centered on teaching stuff rather than offering exercises and tests and solutions are often not provided.
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2 recommended
  1. R Sharma
    R SharmaProduct Hunter · Written
    w3clan is fantastic option to create documentation or tutorial site with option to use "Sub-domain" or "Own Domain" for free. w3clan also offers monetisation with google adsense. Check them out.
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  2. Gaurav Agrawal
    Gaurav Agrawal18Coder, Thinker, Curious observer · Written
    You can contribute to StackOverflow documentation for any subject. Add Examples, Exercises , tests whatever you want to make documentation more understandable.
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